This research aims to investigate phenotypic changes in intracellular metabolism and tumor micro-environment associated with the development of castrate resistant prostate cancer (CRPC) and its early response to therapy using a novel synergistic combination of hyperpolarized (HP) molecular imaging probes. Androgen deprivation therapy is the cornerstone of treatment for patients with recurrent or metastatic disease, but eventually patients stop responding to androgen deprivation and develop lethal CRPC. Advances in the understanding of CRPC have led to the development and clinical evaluation of a large number of new therapeutic approaches that effectively retard the growth of CRPC. However, current biochemical, clinical, and imaging biomarkers do not reliably predict the development of CPRC, or its subsequent response to therapy. HP MR is a revolutionary new MR molecular imaging technique providing 10,000-fold signal enhancement for HP 13C labeled probes, enabling rapid, noninvasive monitoring of multiple pathway-specific metabolic processes. Our strong preliminary data in the transgenic murine model of prostate cancer (TRAMP) have demonstrated the potential for using HP [1-13C] pyruvate to grade primary and metastatic prostate cancer. This project will investigate, for the first time, the utility of HP MRin early assessment of CPRC development and its subsequent response to a new 2nd-line anti-androgen therapy. In the TRAMP and human tissue slice models, we will further evaluate HP pyruvate metabolism, with HP probes of perfusion, interstitial pH and necrosis to advance our understanding of changes in tumor microenvironment with CPRC and therapeutic response. To provide the best indication of the individual value and synergistic role of the proposed HP probes, we will combine the ability of human prostate TSCs to better reflect the complex pathology, function, metabolism and androgen sensitivity in situ with information concerning the tumor micro-environment provided by the TRAMP model. In addition to these critical preclinical studies, this project will expand on the successful Phase 1 clinical trial of HP [1-13C] pyruvate i prostate cancer patients by obtaining the first HP MR data on response to anti- androgen therapy in CRPC patients. The long-term goal of this research is to provide companion MR imaging biomarkers that can be used to tailor treatment to individual patients with CRPC and to benefit future preclinical studies of new therapies and subsequent clinical trials. Therefore these landmark studies will greatly impact both the development of new therapeutics for CRPC as well as the new field of HP MR.